1. Field of the Invention
This invention relates to a link connecting rod to be used for transmitting the power of the wiper motor to the pivot shaft in the wiper apparatus mounted on motor vehicles.
2. Description of the Prior Art
There has been known a link connecting rod provided with plate portions 51 formed flatwise by compressing respective ends of a tubular body 50 as shown in FIG. 10, as a conventional link connecting rod used for transmitting the power of the wiper motor to the pivot shaft of the wiper apparatus. The plate portions 51 are fitted respectively with ball retainers of the ball joints, one of the ball retainers is connected with a ball pin secured to a motor arm fixed to the output shaft of the wiper motor through a spherical pair, and another ball retainer is connected with a ball pin secured to a pivot arm fixed to the pivot shaft through a spherical pair, whereby the rotational power of the wiper motor is converted into reciprocative rotation of the pivot arm.
However, in the aforementioned conventional link connecting rod, the center 0.sub.1 of the plate portion 51, which is formed by compressing one end of the tubular body 51, is liable to deviate from the central axis 0.sub.2 of the tubular body 50, therefore the plate portion may be stressed at a position deviated from the central axis 0.sub.2 of the tubular body 50 and there is a problem in that it is not possible to sufficiently utilize the original strength of the tubular body 50 in a case where the large deviation comes out between the center 0.sub.1 of the plate portion 51 and the central axis 0.sub.2 of the tubular body 50. Furthermore, there is another problem in that it is difficult to obtain sufficient bending strength at a position between the plate portion 51 and the tubular body 50. In this case, although it is possible to improve the bending strength of the plate portion 51 by using a pipe with larger diameter as the tubular body 50, it is unfavorable in view of weight of the wiper apparatus.